Operating an MRI apparatus

Patent metadata

Field	Value
Publication number	US-11193997-B2
Application number	US-201916546296-A
Country	US
Kind code	B2
Filing date	Aug 20, 2019
Priority date	Aug 21, 2018
Publication date	Dec 7, 2021
Grant date	Dec 7, 2021

Abstract

A method of operating a magnetic resonance imaging (MRI) apparatus includes exciting a body coil of the MRI apparatus to emit a radio-frequency signal, determining a center frequency of a resonance curve of the body coil, and calculating a magnet target frequency based on the determined center frequency. A magnet is ramped to the magnet target frequency.

First claim

The invention claimed is:

1. A method of operating a magnetic resonance imaging (MRI) apparatus, the method comprising:
computing a first magnet target frequency based on a first tolerance window; and
computing a second magnet target frequency based on a second tolerance window;
selecting a magnet target frequency from the first magnet target frequency and the second magnet target frequency; and
ramping a magnet of the MRI apparatus to the selected magnet target frequency.

2. The method of claim 1 , wherein the first tolerance window has a bandwidth of at most 5 kHz.

3. The method of claim 1 , wherein the second tolerance window has a bandwidth of at least 10 kHz.

4. The method of claim 1 , wherein the selected magnet target frequency is the first magnet target frequency when a magnet frequency is to be determined using a probe during a ramp procedure.

5. The method of claim 4 , wherein the probe comprises a field probe or an array shim device.

6. The method of claim 1 , wherein the selected magnet target frequency is the second magnet target frequency when a magnet frequency is to be estimated using a current sensor.

7. The method of claim 1 , wherein the selected magnet target frequency is the second magnet target frequency when a magnet frequency is to be estimated using a Hall sensor or a fiber-optic magnetometer.

8. A magnetic resonance imaging (MRI) apparatus comprising:
a first frequency determination module configured to identify a first magnet target frequency based on a first tolerance window;
a second frequency determination module configured to identify a second magnet target frequency based on a second tolerance window;
a selection module configured to select a magnet target frequency from the first magnet target frequency and the second magnet target frequency; and
a ramp module configured to initiate a ramping procedure to ramp a magnet of the MRI apparatus to the selected magnet target frequency.

9. The MRI apparatus of claim 8 , wherein a field strength of the magnet of the MRI apparatus is at most 1.0 Tesla.

10. The MRI apparatus of claim 8 , wherein the magnet is a superconductive magnet.

11. The MRI apparatus of claim 8 , further comprising a current sensor arranged to measure magnet current,
wherein the current sensor comprises an ammeter shunt with a long-term measurement accuracy in the region of 500-10,000 ppm.

12. The MRI apparatus of claim 8 , wherein a bandwidth of the body coil comprises at most 50 kHz.

13. In a non-transitory computer-readable storage medium that stores instructions executable by one or more processors to operate a magnetic resonance imaging (MRI) apparatus, the instructions comprising:
computing a first magnet target frequency based on a first tolerance window; and
computing a second magnet target frequency based on a second tolerance window;
selecting a magnetic target frequency from the first magnet target frequency and the second magnet target frequency; and
ramping a magnet of the MRI apparatus to the selected magnet target frequency.

Assignees

• Siemens Healthcare Gmbh

Inventors

• Biber Stephan
• Bampton Adrian
• Vester Markus
• De Oliveira Andre
• Model Volker
• Nistler Jürgen
• Potthast Andreas
• Johnstone Adam Paul

Classifications

• A61B5/055

  involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging · CPC title

• G01R33/54

  Signal processing systems, e.g. using pulse sequences {; Generation or control of pulse sequences; Operator console} · CPC title

• G01R33/3815 Primary

  with superconducting coils, e.g. power supply therefor · CPC title

• G01R33/381 Primary

  using electromagnets · CPC title

• G01R33/389

  Field stabilisation {, e.g. by field measurements and control means or indirectly by current stabilisation} · CPC title